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Running additional driving lights

Discussion in 'Fuel System & Electrics' started by Xhai, Nov 9, 2019.

  1. Xhai

    Xhai Member

    Hi guys,

    Hope everyone is enjoying their weekend!

    I’m after some advice regarding additional driving lights. I like the idea of having more light when driving at night and love the look of bumper mounted lights like the pics below.

    :D Note the photo of the Libyans in a bus from Back to The Future! :D




    Spotties aren’t really appealing as I won’t be doing much rural night driving. I’ve found some round chrome “driving lights” with H3 bulbs online.

    Thoughts on this idea/hooking them up?

    Would I be best to run them from my secondary battery via a switch on the dash? Or connect into low beam terminals at fuse block (maybe running 4 lights would draw too many amps?)

    I guess there are legal aspects for brightness to consider too :confused:

    I appreciate any insight.

    Syncro27 and David H like this.
  2. Barry

    Barry Well-Known Member

    Abbotsford NSW
    I would see if you can get some LED ones.
    I have some on my T3
    Much lower amps

    On a T3 there is a tab on the fuse block that powers when ignition is on.
    That is what I used and put an inline fuse.

    I wouldn’t just be tapping off the low beam fuse.
    You could tap a relay in there though.

    Also wouldn’t go the switch way.
    Not unless you put a warning buzzer in case you leave it on and flatten battery.
    Xhai and David H like this.
  3. oldman

    oldman Super Moderator Staff Member

    Avalon Beach NSW
    Pretty sure that legally, secondary lights....spotties or otherwise....must be wired through the headlight dimmer switch AND must have a separate isolating switch.
    ie, switch off, no extra lights come on when you hit high beam.....switch on, all lights will now illuminate.
    Separate wiring with a dedicated relay is how mine are. As always, consider the rating of the globes before selecting the wiring you’ll be using and don’t overload the circuit including the fuse/s.
    Xhai, Maxa1967 and Grantus like this.
  4. drivesafe

    drivesafe Active Member

    Hi Xhai, as a rule of thumb, when you have a dual battery setup, anything that is going to be used only while the motor is running, like driving lights, fog lights and compressors, should be wired to the cranking battery.

    This gives you the shortest cable distance from the alternator to the device, which minimises voltage drop.

    Anything that is going to be used while the motor is off, like 12v fridges, camping lights and phone/camera/iPad chargers, should be wired to the auxiliary battery.

    This reduces the chance of over discharging the cranking battery.

    This is just a suggestion for your setup.

    Because the battery is in the rear and this means a long cable run to the front, Try using 8B&S cable ( 7.9mm2 ) for the positive ( + ) cable from the cranking battery’s positive ( + ) terminal to a relay up near where you are going to fit and wire the driving lights.

    With 8B&S cable, you can safely fit up to a 40 amp, ( a standard 30 amp In-Line fuse holder and fuse would be ideal ) which should be located as close as practical to the cranking battery.

    Using the 8B&S dramatically reduces the voltage drop over the long cable run. This means less energy lost in the cable through heat, and with a small alternator as in the standard Kombi, every bit of energy saved is a benefit, particularly when you also have a dual battery system installed.

    Up front, as per each state’s requirements ( same as the ADR for driving lights ) you will need to activate the driving lights when you turn on high beam and you will need fit a switch to be able to disengage the driving lights separately from the high beam.

    Two suggestions about this switch. First off, while the regulations require a switch, there is no stipulation where this switch has to be located.

    For example, in my last 6 or 7 vehicles, to avoid drilling holes in the dash, I simply made up a small bracket and mounted the switch under the bonnet.

    Second suggestion for the switch, I always use an ON/OFF/ON type switch and wire the centre terminal to one side of the driving light relay’s coil ( Relay Pin 86 ) and pin 85 to earth.

    The one side of the switch I wire to the headlight high beam wire.

    The other side of the switch, I wire to a permeant positive ( + ) source.

    By wiring the switch this way, centre position is OFF, one side ON position will operate the driving lights only when the headlights are on and high beam is selected.

    The other side ON position will turn the driving lights one at anytime and this has a couple handy of uses.

    When you first fit the lights, you will need to aline them. Easiest way to do this is to find a long flat and straight bit of road at night. Turn your headlights off and then turn turn your driving lights on with the switch.

    This makes it very easy to aline the lights exactly where you want them pointing, with out trying to work out which is your high beam light patten and which is your driving lights patten.

    The other handy use is when you go camping, you may need some additional light at night, say to light up a campsite when you first get there, and the switch allows you t use the low power consuming LED driving lights without having any other lights on.

    With the switch mounted and connected to your relay, you can then run the cable coming from the rear, to Pin 30 on the relay.

    A HEADLIGHT RELAY will have two 87 pins. You connect one driving light positive cable to one of the 87 pins, and the other driving light’s poise cable to the remaining pin 87.

    You can simple earth each driving lights negative wire to a good solid metal earth in the kombi. The chassis is preferable.
    Mordred, Surfing72 and cbus like this.
  5. Xhai

    Xhai Member


    Thanks for the advice guys. Always good help on this forum.
  6. Xhai

    Xhai Member

    Thanks for taking the time to write such a detailed response @drivesafe Great info!

    I’ll go the route you’ve suggested - being able to operate the lights seperate from high beams via the switch is perfect.

    Makes sense to keep it seperate from the aux battery too.
  7. drivesafe

    drivesafe Active Member

    Another tip, 8B&S is a tad thicker than yellow crimp terminals will accept, but if you cut off a few copper strands, the cable will fit perfectly into yellow crimp terminals without causing any voltage drop.

    Also note, yellow crimp terminals are rated at around 45 amps, depending on the brand/quality. Again making them completely suitable for your application while at the same time, simplifying your work.
    Marlyn and oldman like this.

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